Interest of an intraoperative limb-length and offset measurement device in total hip arthroplasty

Introduction: Total hip arthroplasty (THA) seeks to restore a stable, mobile and pain-free joint. This requires good implant positioning and peroperative restoration of limb-length and femoral offset. Hypothesis: A mechanical measurement device (length and offset optimization device [LOOD]) fixed to the pelvis can optimize lower-limb length and offset control during THA performed on a posterolateral approach. Patients and methods: Two prospective THA series were compared: 32 using the LOOD and 26 without. Patients with more than 5 mm preoperative limb-length discrepancy were excluded. The intraoperative target was to restore individual anatomy. Radiographic analysis was based on pre- and postoperative AP pelvic weight-bearing views in upright posture, feet aligned, with comparison to peroperative LOOD data. Results: Mean deviation from target length (i.e., pre- to postoperative length differential) was 2.31 mm (range, 0.04-10.6 mm) in patients operated on using the LOOD versus 6.96 mm (0.01-178 mm) without LOOD (P = 0.0013). Mean deviation from target offset was 3.96 (0.45-13.50) mm with LOOD versus 10.16 (0.93-28.81) without (P = 0.0199). There was no significant difference between operative and radiographic measurements of length deviation using LOOD (P = 0.4); those for offset, however, differed significantly (P = 0.02). Discussion: The LOOD guides control of limb-length and offset during THA on a posterolateral approach. Reliability seems to be better for limb-length than for offset. It is a simple and undemanding means of controlling limb-length and offset during THA. Level of evidence: III, prospective case-control study. (C) 2012 Elsevier Masson SAS. All rights reserved.